Oxygen Atom Chemistry on Mesospheric Ice Surfaces

Sri International, Menlo Park CA

Investigators

Abstract

A 3-year program is proposed to explore the interactions of atomic oxygen with ice surfaces at temperatures relevant to the high-latitude summertime mesosphere. In particular, experiments are proposed to quantify the loss rate of atomic oxygen on ice surfaces and to investigate atomic oxygen effects on the heterogeneous formation and growth rates of ice. Oxygen atom recombination will be studied using a Knudsen cell reactor, together with laser-induced fluorescence and mass spectroscopic species detection. Atomic oxygen effects on ice formation and growth will be investigated using a cryogenic test chamber, Fourier-transform infrared (FTIR) spectroscopy, and optical thin-film measurement techniques. The overall goal is this work is to provide experimental information to identify and clarify possible roles of mesospheric atomic oxygen in heterogeneous atmospheric chemistry and ice dynamics. The results of this project will aid in interpreting measurements of oxygen-atom and ice-particle distributions in the high-latitude summertime mesosphere and will provide insight for constructing numerical models for mesospheric phenomena such as noctilucent clouds (NLCs) and polar mesospheric summertime echoes (PMSEs).